Please help me!

[Kururu]

So, I have a Ball Python who is almost 2 years old and hasn't eaten in over a month. Not a big deal, right? But, he's losing weight!

I've been recording his weight throughout this month:

February 1st: 890g
February 7th: 875g + Shed cycle begins
February 15th: 885g + Still in shed
February 18th: 880g + Still in shed
February 19th: End of shed + Didn't eat
February 20th: 865g
February 22nd: 855g

He just isn't eating. When I first got him on September 26th 2015 he ate just 2 days after I got him. He was always such a good eater, but since late January when he was coming onto his 3rd shed (he was actually in shed when I got him) he just isn't wanting to eat. I've tried feeding him at night and in a dark room and he still doesn't care. I live in the UK, which means it would be illegal to feed him live food - and I wouldn't attempt it anyway. He only seems to like eating mice, which means he was always fed a little more frequent than if he was on rats. It just seems to keep going downhill since he starting shedding and since I bumped up the humidity to 70%. Since he finished shedding I changed the humidity and overall temperature back to how it's always been: 50% humidity and a temperature gradient of 75-85. Nothing has changed in his vivarium. I clean it out ever 3 weeks, I give him fresh water every other day, he has two hides on either side of his vivarium, I give him a soak every 2 weeks, I check his heat and humidity twice a day, and I've recently checked him for mites, RSI and mouth rot and he's perfectly healthy!

I've been told it's breeding season, but it's almost March.