I’m sorry your bun is poorly. It’s very good that you’re giving us a detailed description.
It’s very difficult to say what is the root cause of this. A bath can be traumatic to a bun, and stress can affect the workings of the GI system. Fleas would have made him itchy, but not produce lethargy unless the infestation was really bad and had been going on for quite some time.
I don’t think deodorant is extremely toxic to rabbits. Some people use perfume or soap on stuff they don’t want their buns to chew, and Ive never heard of buns being poisoned that way.
Stasis is a symptom of something, but exactly what can be figured out by your rabbit savvy vet. What’s important now is to get him through the weekend. The meds you were given are the standard meds that is given if you are certain the bun doesn’t have an intestinal blockage. I think the vet ought to have given you loxicom to distribute at home, and they could have given sub q fluids to perk him up. If you can contact the vet, maybe you could ask. Pain relief is very important for rabbits, they are very sensitive to pain.
Don’t give him any flea/more treatment until you’ve spoken to your real vet. Keep him warm. Syringe feed him so he has food in his tummy. Many small servings are better than few big meals. Try to entice him to eat by offering fresh herbs (parsley, cilantro, full, mint, Basil). If he likes fruit he can have fruit because anything he wants to eat (within reason) is good now. I and many other rabbit owners give baby gas drops (simethicone) when our buns have a stomach ache. There’s no scientific evidence of its effectiveness in rabbits, but Medirabbit says you can give it on suspicion of gas. ((Gas is very often a consequence of gut stasis).
This is my favorite article about gut stasis in buns, it has many helpful tips. It’s written by Dana Krempels, a very trustworthy rabbit expert:
http://www.bio.miami.edu/hare/ileus.html
You can massage his tummy like in this video: http://m.youtube.com/watch?v=JnuxGLa2reg