I Am Going Crazy On Thinking Whether I Have Colon Cancer

Hai guys,i am 20 years old male and I got diarrhoea when I took antibiotics for allergic rhinitis ,i took doxy and ketasma and each time I took these tablets I experienced pain in my lower abdomen and then I took azithromycin and my problem started,i started to have diarrhoea with mucus all these happened in december 2004 I had this diarrhoea for one month as I would excrete only once or twice in a day and then I went to a local doctor january 10 2005 as I experienced some pain inside my lower left rib cage and for diarrhoea the doctor gave me ciprofloxacin,furozolidone and ranitidine tablets and then I got my stools right,then after one month on febraury 9 I had heartburns, nausea and vomitting with diarrhoea with mucus,i went to the doc again and he admitted me in the hosp and carried out an endoscopy(gastroscopy) and diagnosed moderate antrium gastritis and mild bulbar duodenitis and treated me with cefotaxime and ranitidine intravenously and then I felt better and got discharged from the hosp.Then again I had diarrhoea with mucus immediately after the hospital phase.I experience some pain in lower abdomen only while excreting and I have diarrhoea with mucus only in the mornings after drinking water and I also experience some pain in lower abdomen.I have shed 5.5 kgs in last three months but I am still on diet.The doc says that I have ibs and treating me with lomotil and pantprazole 20mg.But still I get mucus in my stools.I must stress this point that when I excrete the first half of the stool comes in a solid way and then the other half is loose motion with mucus.I also experience hairloss in my head legs etc.I feel hungry some times and loss of appetite sometimes I continuously belch for nearly two hours after meals.I feel debilitated and also pain in my muscles.I have also tested for leptospirosis and the titre value for microscopic agglutination test is 100.Guys should I have colonoscopy and please help me with your valuable advice.I get foul smell from my mouth often.Please help me I am very afraid whether I am afflicted by colon cancer.