First, see if rolling a tennis ball under your arch helps. This won’t solve any longterm problems, but it may give some immediate relief. I don’t know what you are permitted to wear at work, but you should find a store that understands the proper mechanics of fitting feet. If you are having some sharp pains under the arch and possibly in the heel, chances are you are developing plantar fasciitis. It’s pretty common, though it does require some rehab to repair, which can consist of proper shoes (it would need to be what’s called a motion control shoe most likely), perhaps some good orthotics (some generic ones won’t work that well), and some stretching (which you could probably find a demonstration online, or there is something called Strassburg Sock, which you can purchase).