I am sorry to hear that you are having this severe pain. You should definitely get in to see a doctor
about this, either a podiatrist
or your primary care doctor
, because there is likely treatment options available to you.
I think the most likely cause of your pain, based on the symptoms you describe, is something called plantar fasciitis. This is a condition in which the connective tissue in front of the heel bone becomes inflamed, leading to pain particularly with walking. Your doctor can confirm the diagnosis for you with a physical examination although, based on your history and risk factors, they may also want to perform other tests, such as an x-ray, to rule out other causes of the pain such as a stress fracture or bone spur.
If the diagnosis does turn out to be plantar fasciitis, your doctor will be able to recommend treatments, including anti inflammatory medications for pain, exercises to help stretch out the tissue in the arch of your foot and back of your calf, and proper footwear to support your arch and help the inflammation settle down more quickly.
Get in to see your doctor as soon as possible, and good luck.