Plug or not????

Okay so this is kinda gross but I'm not sure what is so I'm hopping someone can help me out! 
I'm 36w5d me and my husband had sex this morning and right after I started spotting but I know that can be normal but after I noticed the spotting I looked down at the toilet and saw some pink chunks at the bottom of the toilet could that be my plug? It sunk right away so I'm not sure but I know sperm dosnt just sink like that and there was quite abut of it so from today I've been just crampie and if I try to get up after laying down for to long my body feels sore and stiff has anyone else gone through This???