You could have an internal hemorrhoid or if visible and external one. You could also have torn something inside the anal wall. As long as the blood is bright red and not dark, this should not be a problem. Straining will most definatlly casue hemorrhoids! Eat more fiber and drink more water.....everyday. You could also try adding (benefiber) to your diet or an equivalent!

It sounds to me like hemmeroids (Sp?). They sell suppositories foer that type of thing but it would be smart to go to the doctor to make sure thats what it is. Good luck!