Pins & needles tingling sensation in heel.

[bossychloe]

Hi, For the past 4 or so days my left heel has developed a 'pins and needles' type tingling when I put my full weight on it. It is not too painful but it is extremely uncomfortable. I constantly find myself walking on tip-toe to try and lessen the sensation.
The only time it doesn't tingle is when I wear high heels, then the heel feels like normal.
If I try to straighten out my left leg and flex my foot it really seems to pull and puts more pressure on the heel and I get that dreadful tingling sensation and if during any stretching I (with my legs straight) try to touch my toes it is truly dreadful - it feels as if it could snap something inside!
Has anyone any idea what I have done or what I can do to remedy it?
Thank you.