HELP!!! Is this common during in heat

Hi I have a 7 month old American Staffordshire terrier. She is an amazing dog I just got her 2 months ago. She is currently in heat, she is almost done on her cycle. She has maybe couple more days left :) I hope everything goes welll!! But I’m a lil worried. I noticed she had this small pimple though it was because she in heat but I noticed today it got so big. Is this something I should worry about and take her to vet? 

Hello - yes, we do think this is worth booking a veterinary appointment for.  Depending on what is causing the lump, it may simply go back down after the season.  However, the lump may 1) alter the case for speying, 2) come up again with future seasons and it may 3) merit a biopsy, so it's worth talking over with them in the context of your particular pet.  Please do let us know what you decide for her.