Feet hurting?

This isn't a pregnancy question, but I wasn't sure where else I could ask it: so I am about 315lbs, and my feet hurt. Bad. Especially my heels. This is a relatively new thing... maybe as of like 4 months ago. I have googled it and believe it is plantar fasciitis, but it may just be too much weight on my feet. I know the obvious answer is to lose weight, but going for walks have gotten so painful that even minimal exercise is not really an option. I have a toddler and would love to run around and play with him, but I end up paying for it in the end. I am a teacher so I am on my feet a good bit, but by the end of the day I'm miserable.

Any advics/tricks/remedies???

Thanks!!