Need advice on this odd insomnia issue.

I have always been a light sleeper. A pin drop can wake me. I been on medications for the past year that just happen to help me sleep so I been sleeping well for 12 months then out of the blue statarting mid March I been having insomnia. Going from 7-8 hours sleep a night to 4-5 hours of sleep. I monitor my sleep with apple watch and for some reason, out of the blue, not a gradual change, I went from solid sleep to waking up every 10-20 minutes. 7-8 hours in bed about 2 hours of that is awake spread threw out the night. i also noticed i am not getting any REM or deep sleep. According to apple watch all sleep i get is core sleep
I rotated and flipped mattress, added a feather bed, take melatonin, I take my antidepressants at night that knock me out. I am "comfortable" when i go to bed but wake up sore and stiff every 10-20 minutes. Now i noticed a pattern that this happens every spring. Can the change of seasons cause this? Also my apartment is exceptinally hot. Building is on radiator heat and its still kicking out heat in April! That may be a factor.

Anyways nothing changed as far as stress or diet and I was recently at the doctor and all my blood tests looked good. I am taking daily supplements, joint supplements. I do not have stress or racing thoughts. I cant seem to figure why its happening.