Why Are Antibiotics Making Me Feel Better?

Howdy folks!  Like most of you, I'm looking for answers.  I'm post-cholecystectomy and post-sphincterotomy.  My pain is undiminished.  After a recent rx of Flagyl, I noted that I felt better although the pain was unchanged.  About six days after the end of the rx, I started to feel sick again until I could barely walk and was throwing up daily.  I've been keeping a blog on medhelp.org and I started to put my brief (but joyeous) improvement together with the Flagyl and my doctor ordered another rx last Monday.  Well, I woke up this morning and I felt better.  It took me ten minutes to get out of bed instead of an hour.  The constant pain is brutal but, for the most part, pain can be managed.  If anyone has any idea why antibiotics are providing a reprieve in nausea, vomiting to bile, extreme fatigue and a lack of mobility, I would love to hear your take.  
Take care of yourselves and each other and thank you all for your time.  Have a great (pain-free) day!