Digestion problem

hello doctor,
most of the time when i drink milk ,have any milk products, or any heavy meal my stomach gets upset, my digestive system dosnt digest it, (dierhea),after that usually I take 1 dose of any antidierheal medcine ,and  have only light meal then my diegstive system gets normal in 1 -2 days... i have been suffering this problem since Feb 2008( at that time i had a sever dierhea, vomitings) ... i think my digestive system has become weak, thats y it cannt digest normal things which all people digest easily...
i have dierhea 3-4 times in a month :(..one more thing i want to mention is that i dont go to bathroom soo frequenly when i get this dierhea,, i just need to go 1-2 times in a day but my poty has lots of bile..and after taking medcine it gets normal to some extent..i mean it remains soft with less bile in it..  i also have UTI problem, i post that in urology forum. plz suggest me some home remedies too..
look forward to see ur response