Stomach Infection again and again.

Since last 6 months as per drs I am having stomach infection again and again I lost 8 Kg weight as well. Problems are: Cramp, Semi digested semi solid motions frequently, weakness, lazziness, feeling so low, bloating, sometime little little pain, nausea and this time I had body shivering as well. Problem becomes better for sometime then again occurs. One Dr prescribed many test, consulting Best Gastro of my locality he is saying it's nothing but ibs due to which I am having these issues. I am not using outside food, only bislery water total hygiene still unable to recover. USG, CBC- OK, LFT earlier problematic now ok. I am afraid that I am having some serious issue. Pl suggest what to do.? Should test require? Sometime constipation also there. If any one from NCR is here who can devote some time on my history and get it resolve I am ready to meet you pl help