Best tips I can give:

• Soak them regularly with Epsom salt or dead sea salt for pain.
• Adding some ACV to just a warm water no salt foot bath will help soften and loosen layers of skin buildup such as calluses or corns.
• A corn removing DIY is crushing up an aspirin and making a paste with a little warm water and some lemon juice and applying to the corn and putting a bandaid on it for 10-15 minutes. Then take it off and rinse off and file with a foot file. I like the Flowery Swedish clover foot file. It's the red one. It's under $10. Then rub feet with castor oil and cover in Vaseline (optional) and put some fuzzy socks on.
• If shaving down a callus soak the feet first but then dry them well. Then use a callus remover tool. I recommend looking at some of The Meticulous Manicurist's videos on YouTube. She explains so much about foot health and pedicures.
• When removing said callus/corn only remove 80% of it at the first go. Otherwise the foot will think it's been injured and have an inflammatory response to attempt to heal the raw skin which would create even more pain that you don't want or need and possibly scabs/blisters on top of where the corn used to be.
• If the pain is in your foot muscles I would look for some spiky massage balls. I use these.
• For shoe fit you need to find out if you over-pronate, under-pronate or are neutral. These are ankle positions that affect your gait.
• Also find out if you have high arches, medium/neutral arches, or flat feet. This can help you find insole support.

Hope that helps your feet.