Oobie, you've left out a key piece of info. How is your weight? If you're overweight and/or eat a lot of sweets, it could be diabetes, or you could be having intestinal yeast problems. Stop. eating. sweets. now. It's the best thing you could do. Even better, and esp if you are overweight is to do an Atkins type diet. Eat protein and veggies and limit the carbs and fruits for a while. You may feel worse at first, esp if you have the candida albicans problems that it sounds like you do, but keep it up and you'll feel better. Some doctors do put their diabetic patients on Atkins and are able to reduce or eliminate diabetic meds altogether. Also, please don't drink diet sodas--you don't need soda at all, but aspartame can contribute to dizziness or worse. Splenda I don't know much about, but after very scary probs with aspartame, I don't trust any of them.
As for your foot problems, it sounds like you have the same thing I do--plantar fasciitis. Do your heels feel bruised in the morning and do you hobble around for 5 or 10 minutes to get them loosened up and then they feel fine, until you sit down again and then have to do it all over again? Um hm. Your shoes would indeed be the problem but the bad news is that you'll have to spend at least $100 for a decent pair of shoes with good arch support. Go to a full service shoe store and get properly fitted and ask which shoes are the best for those with PF. My guess is that you've been having probs with your feet since you were pregnant with your daughter--that's when mine started. I love my Klogs, but there are other excellent brands out there. If you go to a doc he will shoot your feet full of cortisone, which will give temp relief, but then he'll recommend shoe inserts to the tune of $300. The shoes will do just as well, so spend the money on good shoes and you'll be ahead.