Intermittent nausea, gas, stomach disomfort

Over the summer I was in Tanzania, Africa for just under three months.  While I was there, I was diagnosed with and treated for malaria and was experiencing many different symptoms, such as extreme nausea, stomach discomfort, dizziness, headache, loose stool, etc.  When I returned home to the US, some of these symptoms had stayed with me, such as nausea (although much less frequent and better after a meal), stomach discomfort, intermittent loose stool, and gas.  It has been almost five months since I have returned home and these symptoms are still present.  I have never experienced these symptoms with this much frequency before I had left for Tanzania.  

When I returned home from Tanzania, I had a lot of blood work done to see if there were any malaria parasites left in my blood, but the tests came out negative.  However, I have not had any other tests done.  I am not sure if this is caused by something that I could have ingested or if it was coincidental timing and it is something completely unrelated to my trip.  

Are there any specific tests I should talk to my doctor about?  I would love to hear any recommendations that I can tell my doctor about.  Help will be extremely appreciated.

Thanks,
J.C.