Tomato problems?

Tomato problems?

Help! I'm trying tomatos this year in a pot (they were labeled as patio sized at Lowe's). So far so good. They've grown, and I have one tomato that is about 2.5" in diameter already, plus a bunch of flowers, so I think they're growing well. Problem is, the leaves are yellowing and drying up from the bottom up-I've been trimming off the damaged leaves as they happen, but it's continuously happening, and I'm only about 3 levels down from the existing tomato at this point. If it keeps happening, I fear I'll lose the one tomato I already have. Any ideas? Sorry I don't have a photo of it, our camera's out of commission today....
a freshening of my bedroom

a freshening of my bedroom

beginner’s update

beginner’s update

Our light set up seed thingy

Our light set up seed thingy

My livingroom

My livingroom

Plant Name

Plant Name

A question of sweet potatoes.

A question of sweet potatoes.