Should i be worried??

Price • Together for over 13 years, married 6 years. After 3yrs ttc w/PCOS we finally have our son! now without trying we r pregnant with baby #2
We went for our 8 week ultrasound this morning and everything was great. Had a strong heartbeat of 175. But i have been feeling this pinching / cramping feeling all day plus after the appointment i saw a very tiny amount of blood on the tissue after wiping. Should i be worried or do u think its just from the ultrasound?