I have a pain in my inner heel that came from nowhere with no reason, it hurts to walk on it and apply pressure. what's going on?

Need more: Sudden onset? Hx of osteoarthritis, rheumatoid arthritis, osteoporosis, trauma? May be anything as simple as plantar fasciitis or heel spur to metastatic bone cancer. I would seek eval by your primary care physician - a history and physical exam can hone in on the issue it may be resolved w/ simply a change in shoe wear, imaging may be required or may be more extensive - good luck.

Couple of things: You may be suffering from plantar fasciitis or you may have a problem with the nerve. Either way you should see a podiatrist.