With a normal physical? most likely IBS.Even the lactose issues can sometimes only be painful and cause diarrhea if you have IBS (many people who test positive for lactose intolerance have no symptoms, and most of those with symptoms seem to have the same ones IBSers have from any food that can feed colon bacteria and lead to gas).IBS doesn't show up on normal physicals because they are not doing the medical tests that can indicate IBS. Like they look at the TV and say the TV works, but then don't check the remote and the remote is what is not working. In IBS it is the nerves involved in control and sensory functions of the gut, and most tests don't even look at those (there is a new IBS blood test that is the first to look at those things and has a few blood markers that indicate it could be other problems).You might look at how much starch you eat as that can increase gas and some IBSers with gas and diarrhea seem to do better when they limit starchy and some sugary foods that really feed the TOTALLY NORMAL colon bacteria.You could look at Probiotics to reduce gas. Or try simethicone with ever meal for a few days to see if that helps. (Wind-Eze, Gas-X). Peppermint can be good for pain, teas, capsules, or I use peppermint Altoids that are made with real peppermint oil.IF those sorts of things don't help, then find a doctor who actually believes that IBS is a treatable condition and see if any of the prescriptions for IBS helps.