Small rubbery lump under stomach skin

I had my baby 9 weeks ago and have some pretty epic stretch marks. I’m a fluffy mama to begin with (size 16/18 pre pregnant) and I was rubbing some lotion on my stretch marks and noticed a little rubbery blob under my skin in my upper stomach. It kind of feels like a soft rubbery grape. It’s smooth and the skin on top rolls over it easily. Any ideas?