Hi ,
I have had intense foot pain with my RA. Sometimes it is more of a dull ache, but at other times I have had intense pain that may be what you are experiencing. I've had this due to two reasons: the plantar fasciitis that Franki referenced and bunions. While these are both conditions that can happen to anyone, my rheumatologist told me that RA exacerbates these and can make a person more likely to experience them.
Plantar fasciitis felt like I was getting stabbed in the foot and was excruciating. Luckily, high doses of anti-inflammatory meds and doing the exercises I was given made it go away over time. One of the exercises was rolling my foot over a frozen water bottle, which simultaneously exercised the area and iced it.
With the bunions, my doctor told me there isn't anything that can be done until I'm at the point to have it surgically remedied. I am very careful about the shoes I buy, as shoes that put any pressure on my bunions are very painful. I have to opt for brands with a wide toe box. I also use a shoe stretcher for leather shoes that aren't quite wide enough.
Be sure to discuss the pain you're having with your doctor so that s/he can help find options that might help. I hope you find some relief soon!
Wishing you all the best,
Tamara