What would cause a vibration sensation in my right foot?

[Rpinter]

I am a teacher and one day last week I had been particularly active with several trips up and down the stairs.  After lunch, I suddenly felt severe pain in the ball of my foot and by that night it was hurting so badly I could barely wear my shoe.  I also noticed what seemed to be bruising at the base of my toes (on the top of my foot).  The odd thing is I don't remember anything "happening" to cause this.  The next day I wore more comfortable shoes, tried not to stress it, and by the end of the night it seemed like it was healing.  Yesterday I noticed a "vibrating" sensation in that same foot - just like described by several on here - every 2 to 3 seconds and unaccompanied by pain.  I really can't afford to go to the doctor since Obamacare.  The last time I went for a severe cough/bronchitis and I ended up paying almost $300 because they ordered x-rays.  With something like this,it would probably be more like $600-$800 because I am sure they will want to order x-rays and have me see a specialist.  On a teacher's salary in Oklahoma at a Christian school, so I don't have much of a nest egg to spend on health issues.