Wondering if this was a miscarraige?

i am on the pill and i always start my period on a tuesday or wednesday. well tyesday light cramps no blood nothing, wednesday crampong but only brown no red blood at all only spptting and dark brown. thursday i gushed blopd the only time that day and went to the bathroom and saw a long pinkish, tannish colored skinny almost stringy but a real rubbery not mushy at all thing, it was curled up in my panties..after that my tamppn had a few clots i think but now there is just bright blood regular and not heavy flow and brown too again which os weird bc i dont usually have brown unless its the first or last dau pf my period. im still cramping and back hurts bad. also wednesday before all this happened my lower right side was so sore everytime id stand up is this a ppssible moscarraige?