HELP!!! boa is having bad bowl movement

I have a 6ft boa she hasn't pooped in 3-4 weeks I fed her a rat 3 weeks ago and another one a week ago and now she's pooping out watery brownish red stuff looks like water not the runs and its a lot and she had a lot of foam bubbles coming out too and is farting a lot she's been doing it for 30 mins now I have paper towels in the bottom of her cage that's what I always use and there all soaked now there a lot of liquid coming out and 2 piles of the white stuff so far but no brown solid pieces anywhere like normally. her tails been up too for the past 30 mins it don't look good I never seen it before and I had her and other boas for 8 years now. Does anyone know what can be wrong? Any help will be appreciated. Thanks

It sound like possible constipation or just a really massive dump. Optimum humidity and temperature are needed or feces cant be come hard or "cooked". You said she exhausted some white stuff which may be urates depending on consistency but fact you mention blood makes me believe it's a job for the Vet. The way I'm reading your post it sound like there is some major strain going on & possible tearing.

I would definitely see a Vet to be safe as possible but in the mean time verify your temps & humidity. A slightly warmer then room temp bath for about 15/20 minutes may also help loosen any blockage making the passing of a painful stool possible.

Just out of curiosity do you house this animal alone? Think carefully, was there any possible chances for her to attempt breeding?