Possible anal fissure. Really worried.

I'm 28 years old and about 3 weeks ago, I had some diarrhea after eating something bad. At the end of that "diarrhea session", there was a small amount of blood on the toilet paper after straining for a long time, could almost feel a tear happening. Anyways, I called my GI(who i saw for acid reflux months earlier), who said to increase fiber and water and thought it was hemmorhoids. I unfortunately didn't follow those instructions and it happened 2 more times in about 2 weeks. Today marks the 4th time in 3 weeks it's happened. Sometimes I've also had the feeling of having to go even after having a bowel movement. The blood is bright red and in very small amounts, and seem to be happening after "straining" or a hard bowel movement. Once, I felt like knives were on the bowel movement when it was coming out. My doctor found an anal fissure and told me to up fiber again. I am moving in a week and is wondering whether I can wait, or do I need a colonoscopy asap? Thank you very much.