Hi Decas,
Looks like you are very worried about this - hope it is improving.
It's not a frequent thing, but it does happen that people experience numbness in a leg - though it is often from much longer sessions than half an hour.
Were you experiencing pressure and pain when you were meditating and trying just to observe it?
Bodily pain often arises during meditation and whether we do anything about it depends on the cause. If we are sitting awkwardly or on a pressure point it makes sense to adjust the position. Some pains arise and pass while meditating and these can just be observed.
A good rule of thumb would be if the pain arises in meditation but is not there afterwards it is just due to the meditation process. If it persists for a long time when not meditating, it probably has some physical cause.
I doubt you can have damaged a nerve by sitting pressure in half an hour - but I am not a medical practitioner. If it is still troublesome and not improving, maybe you should have it checked out.
I would advise changing your meditating posture so you don't put pressure on this spot.
There is something you can try to help your self.
Generate loving kindness that fills your whole being and direct it with compassion towards the foot. Allow this light of loving kindness to bathe the foot.
If you find generating loving kindness difficult, use your imagination. Imagine a small, helpless being - like a puppy, a kitten, a lamb - it is in distress and needs love, care and comfort - allow all your love and compassion to flow towards this imaginary being and then direct that compassion to yourself and to your foot.
sending you much loving kindness
peace and joy
