I Think I May Have Had An Abortion. Should I Go To A Doctor ?

I recently had a bizarre period with spotting for a week( brownish in colour)-followed by its usual pattern( I presumed that my partner and i had been successful in conceiving, yet the fertilised egg had not implanted). My cervix felt irritated throughout this time and continued to feel irritated with led to us having only 1 period of sex( the previous month it had been almost daily) until The following month when i again had a bizarre period, This period was normal in behaviour initially, but i continued to spot ( Brownish in colour) I took 2 pregnancy tests at this time, both of which were positive. I visited a GP who advised that it was probable CM- pregnancy tests too sensitive ect ect-and not to worry. I have continued to spot( not enough to use a towel) and this morning awoke to heavy cramping, feeling nauseous and passing large clots ( Period now 13 days in duration- usual 3 days in length) I can only presume from this that i am in fact experiencing a MC and not a CM and that i was approx 8 weeks PC. Do i need to revisit a GP let nature runs its course?