Small Black Lumps on Dog's Belly?

I have a female English Bull Terrier/Staffi, which is 3 years old. I noticed while stroking her belly, she has multiple weird black/dark lumps, around the size of a small bead. These are located around her belly and her sides. We go for a walk around once a fortnight as I'm quite ill at the moment, but we try give her as much exercise as possible, our walks consist of walking along the beach onto a field where she gets let off the leash so she can run freely. The spots have been there for maybe around 3 weeks.

As I'm quite low on money because of Christmas, I would be deeply upset if something was seriously wrong, the spots are making me very concerned about my pet as she's been a part of my family since she was a pup.

By Jodi H.