For many mammals, alot of movement starts with the limbs. Robert was no longer a mammal, and no longer had limbs period. He took things carefully and slowly, so that he could take notice of things where needed and not confused all that was going on already.
The first thing he noticed was even first attempting something like flopping on the floor or swimming motion in water didn't translate to what he wanted as a maggot. From what he could feel, he literally just squirmed randomly, if slowly. He then tried to move ONE thing at a time, making some progress form random to semi-random and finding out it was a combination of trial and error with what did one and just pure exoticism of his body. Figuring some things out, and kind of getting a sense for his "head" and "tail", he got a feel for translating what did what with his body, although he was nowhere near a full, fluid movement. Walking and chewing and all that.
Full-movement came again, and this time with more success. He wasn't trying to get anywhere, yet, but he did need to figure out to more then one thing since he had no limbs to work with, just one tubish body. With some struggles and tests, he could pull off a few things. A fetal position, reverse fetal position (it had help him figure out where his "back" was, as well as clarify up and down), rolling to one side, rocking side to side, and so on. Most importantly, doing a worm-like movement of bringing his back side into himself and then pushing out with his front. He now could start moving somewhere.
Overall he felt he could spend more time figuring out his body, but he had the urge to just out of his shirt to see if his sight was any better. So he started his journey, deducing that just going somewhere would lead him out of a hole of his shit. Throughout his journey he got more fluid with his movements, using a combination of the worm movement and other ones experimentally but soon seamlessly. He was also able to figure out more of his sight. When things were closer or farther, darker or lighter, but it was too soon to tell obvious shapes just yet. He wondered if he was even taking in things like an actual maggot would. Heck, was his brain still human somehow? It probably was since he figured if he got dumber or felt some weird instincts, he would've encountered such issues by now.
Things taking long enough to make him worried that he was off about his senses and got lost, Robert's senses of smell and feel came to his rescue. First it was just a presence of a third smell, kind of waffing over him. He wasn't sure if it was enough to tell if he was reaching the outside of his shirt, but it seemed to make sense considering he's been in on enviornment so far. Moving towards the smell, he felt a temperature change. He suddenly remember the room he was in was a pretty comfortable one and air conditioned, or at least cooled in some manner. He felt something similar now as a maggot, simple and weird like everything else, but was a welcome sensation to be able to tell temperature. Making a more of a effort, he followed his smell and feel until he hit a bit of a wall. Or to be more accurate, a crevice he couldn't fit in.
Robert figured he hit the collar or one of the sleeves of the shirt, but it was just folded or wrinkled over. Now more familiar with his body, he just moved along the crevice, looking for either an actual open gap or a part he might be able to force himself into. He wasn't even sure how strong his maggot body was to produce any sort of force. Eventually he felt a part of the crevice move and his senses went into over drive. The smell came in stronger then before, he felt a more dramatic temperature change, and pretty sure he felt a gust of wind, relative to the size of his small body. And light! Freedom from the shirt! He didn't care about taking his sight sense slowly, he just wanted out now! Putting all his lessons to use now along with the drive of human man, he was able to squirm his way through the gap and wrinkles.
He was outside his shirt now! Ignoring the sensory overlord, he did his best to swing his head portion around in celebration.