I think i might have a sick Python?

I've had a ball python for 8 months now and i was having problems with eye-caps, so i decided to take the python to a reptile vet. He told me that the eye-caps would come off in the next shed, and he probed the python at the same time and told me that she was female. that was about three months ago, she was ok for a while and the last two months she hasn't eaten or shed properly, she did start to shed two months ago and hasn't shed her skin off yet,and hasn't eaten or passed any excrement. I have a large piece of bark in the tank and a heat mat under the water dish and under the bark i have a moss filled container (which is kept moist) so she can go in, I've noticed tonight that the end of her tale has gone black and hard and round the area that the vet probed her, it has gone crusty and hard. Als her breathing has gone bubbley If you can help or give any advice it would be much appreciated.