It seems like you have had die off. Something has been decomposing in the bowels. Toxins in blood stream can cause these symptoms. The constipation is the same thing. Enemas are good but i think the fleet enemas might not be enough if you are really blocked. The big enemas are better, like 1-1,5 liter water (sea salt and warm distilled water), done slowly. Alao castor oil helps if the blockage is higher up. Take several times a day. Castor oil packs should help too. If you feel better you should continue on the cleanse.
Allergy and constipation, IBS points to a more complex problem which is probably nothing to do with the Antibiotics . Doctors are pretty useless. I would consider a deep parasite cleanse for at least several months. To me reducing parasites resolved allergy, hormonal problems, weight gain, IBS and many other issues i have had all my life. It takes a long time but so worth the effort!!