lyme disease and IBS

I am visiting from the lyme boards. I have have had lyme disease since june and was"lucky" enough to have a bulls eye rash etc. so started right away on abx. However, my IBS has made it extremely hard to tolerate the high dose treatment of abx. and I am getting very frustrated. Would anyone have any advice on what I can do/take med wise to help me tolerate The abx.?  I AM on a very strict diet due to the yeast problems from the abx. no sugar, carbs etc. Any suggestions would be so appreciated.