Chemical pregnancy

Please tell me your experience with a chemical pregnancy. I was getting positive pregnancy test for 2 days. Today I started cramping on and off pretty bad. Now the pregnancy test are negative. Not sure DPO because my cycles are messed up. I'm not bleeding. I have took 6 test today all negative. Should I contact my doctor? What will happen? When should I expect to start bleeding? Will this make my next cycle messed up? Does it make you more fertile? I have never had this happen before. I have been sad all day because I feel upset with myself that my body couldn't keep the pregnancy going.