Yes, I would start with an opthomologist. Do you have one that you've seen in the past? If not, maybe talk to your regular GP doctor, and ask for a referral. That is not something to be taken lightly (hopefully it is nothing serious). Please make the appointment soon. How long ago did this happen?
And do not rub your eyeball to try to clear up a problem. If it had been a detached retina, that is the last thing you should be doing.