Little white bump on my dog's paw.?

My dog is seven years old. He's a deer faced chihuahua.

For the past week or so, he's been licking his paws often, I thought it could have been a new habit he developed or something. I didn't think much of it. He hurt the nail of his right paw a while ago (but it's healed now). I thought it was that. I take him out every day, I try my best to not let him go on the grass too often unless he needs to do his business, and I usually keep him on the pavement (I don't want any ticks or fleas to get on him, which has happened before).

Today my little sister noticed that my dog keeps lifting his left paw. He doesn't complain when he walks, and he walks fine, but whenever he sits or lays down, he lifts his left paw. I checked the nail and it looked fine, but my mom then noticed his left paw pads were reddish (more than they should be). I noticed a small white bump on his paw pad (close to the edge where the fur meets) that looks like a white head pimple or a wart. It's hard when you try to squeeze it, and we couldn't squeeze it because we were scared of hurting him (he kept pulling away). He doesn't look pained but uncomfortable. We think he has an irritation, or he stepped on something. I think it might be a pimple or a wart or something.

We really don't have the means to go to the vet and have him checked by one, especially if it's all for nothing and he's perfectly fine. I really don't know what to do? Should I wait it out for a while? Should I try to pop it? Should I apply something to it? Taking him to the vet is really the last option here because we really can't.

Does anyone have any suggestions or serious inputs as to how to treat him or what it could be? Thank you so much.