Tmi: WORRIED! What is this? My dr doesn't seem concerned.

I am constipated more than I've ever been I found out I was pregnant at 5 weeks I'm now just shy of 7 weeks by a day now. 
I've been experiencing strange symptoms besides extreme constipation, light pink bleeding after straining for a BM. Not even that hard either, just a normal going to the bathroom like everyone probably does. This has happened three times in the past 4 days. 
My dr doesn't seem to be concerned and thinks it's correlated to being constipated and light bleeding is fairly common in the first trimester and everything's probably fine since I am not cramping or in pain or have red blood or heavy bleeding. This is my second pregnancy I have a 3 yr old DD, this never happened while pregnant with her. 
I do have an ultrasound 11/13 but I'm still worried! Anyone have experience with this happening???