Lumps on My Dog?

I have a 5 year old dog. He's a mutt and weighs about 50 pounds. He went to the vet yesterday for a bad ear infection that he's had awhile. When I picked him up I got papers telling me how he did also informing me of things that may need to be checked out, including his teeth and skin masses. The vet didn't say anything to me about his skin masses so I'm hoping that means they didn't find it threatening. I went ahead and made him another appointment to get the lumps on him checked out, but this waiting until I know is killing me. I want some information to maybe get an idea of what it might be until I get him in.

I checked his body and so far that I can tell I found 2 lumps. There is one very small lump on the back of his left ear and 1 a little bigger than the other underneath his left arm in the armpit area. Both are underneath the skin. There are no openings on the lumps and no discharge. I felt around both lumps and they don't seem to be causing him any pain. I have only had my dog for 7 months and I don't know if he had these lumps while I've had him or before I got him. I haven't see any change in him since I've had him. He's always acted the same. Is there anything anyone can tell me to help me know what to look forward to at the vet? Please and thank you.