Lump or duct?

So I was having some nipple pain the other day while nursing DS2 (almost 5 months) and I squeezed my breast close to the nipple (I flattened it like a sandwich) and felt an oval shaped squishy mass, about the size and feel of a grape but not that hard. It's definitely new and I don't have that same feel in the left side. I have had blocked ducts before with both DS1 and DS2 and they felt different and I could feel them without having to squeeze down. Can you get plugged ducts in the middle fleshy part of your breast? I really don't feel like going to the doc if it's just a plugged duct and will clear. Just wondering if anyone else experienced this or if it's even possible before I worry that it is something worse or unrelated to nursing. Also not sure if it makes a difference or anything but the nipple on the affected side is inverted, but it's been like that for years now so I think it's a non-factor.