Update:
I went to bed about 30 mins after my initial post and the pain was excruciating when in bed. I always sleep on my sides but I couldn't manage that due to the pain so I had to sleep on my back for the first time in years. When I got up this morning (about an hour ago), the pain was even worse. It was exacerbated just from looking down at my feet. Putting on my socks was a nightmare. I stretched it out a little bit by bending at my knees, holding onto my door handle and pulling back. This slightly alleviated the pain. From being up and moving around for the last hour, the pain has subsided to a significant degree relative to when I got up, but it is still pretty painful. I'm icing it at the moment and have just taken 2 Ibuprofen tablets. I'm assuming this is completely pointless since I can't appreciate any bruising or swelling which leads me to believe that this is a nerve injury, not a tear.
Any thoughts on what the diagnosis is and how to rehab it? I'm heading into college in 10 minutes so I wont be able to ice it nor stretch until later this evening. If the injury is only a pulled lat, would the Starr rehab protocol be effective or is that specifically for muscle belly tears? I'm really at an odds as to what's going on and I badly need this injury sorted as I have exams coming up in college that involve me moving my body around so I'm fucked if this hasn't resolved in the next week.