if you are getting weaker, it is always one of these issues:
1) nutrition
2) sleep
3) training work load + frequency may be too much for your current work capacity
raptor's comment about considering sleep a workout is great. *IF* you feel fatigued from 5-6 hours of sleep, then it is an issue that needs to be worked out, or you need to reduce the frequency of your training until you are able to adapt to that sleep schedule. Training is CNS intensive; if you are unable to recover properly, at a certain point you're going to take 1 step forward, 2 steps back.. which seems to be your case right now. However, 5-6 hours sleep shouldn't effect your strength too much, especially if that's been your schedule for a while.. A simple ~15-30min power nap can have incredible effects on your recovery/strength, so see if you can get one of those in on some of those 5-6 hour sleep days.
if i had to bet money on it, i'd say your #1 issue is nutrition. You mentioned "eating light to stay light", well, your body probably just isn't at a level where it can do that right now & recover from intense training. Spend this week adding in more lean protein sources and green veggies, see what happens.
You took some time off and are coming back with a vengeance, but physiologically you are not able to handle the current combination of intensity, volume, & frequency combined with those other factors of sleep/nutrition..
How often are you training? You may need to stretch it out more, to allow for some more recovery.. I know that is hard for someone who always wants to workout, but, it sounds necessary at this current time. Instead substitute an intense workout with a light one, such as some light sprints, prehab/activation work, a pool workout, etc..
Finally, just think about the time off you took and how fast you gained strength when you came back. It's a good depiction of "more rest not being a bad thing".
Curious, how often are you training & for how long each session?
peace