ANSWER – The steps you have taken so far seem eminently sensible. I can add three more suggestions. Firstly depending on your friend’s spiritual beliefs you could try blessed water. This is basically water infused with the blessings of the Gods. Not something I would suggest for someone who doesn’t have a belief in deity as it is important to recognise people’s own beliefs when attempting anything that touches on healing work but for somebody open to the idea of the Gods blessed water can be both a powerful tool for the mind to psychologically assist in the healing process and also for the genuine benefit such blessings can bring.
Secondly I’d suggest trying to counteract the crystal with the healing benefits of other crystals. Quartz is a very neutralising stone and may help held closely to the skin of the affected area. Other stones I’d suggest trying include Aqua Aura, Howlite, Kunzite or Tourmaline.
It is important not to overlook the fact that some crystals do react with human skin and can produce unpleasant results. A description of the crystal may have been helpful here. A piece of solid sulphur for example can cause extreme skin irritation in some people. It’s always a good idea to look for practical causes as well as less mundane explanations. I’d go back to the crystal owner, ask him what crystal it was and then do a bit of research on the internet. If it turns out it is a stone that can trigger any problems then a visit to the doctor would make good sense.
If you do confirm the owner of the stone is hostile (and this is a big if as it is highly implausible that anybody would waste this kind of energy on a stranger) then I do have a counter spelling suggestion that will work to break the impact. A simple charm on a crystal of your own which you then persuade him to hold would potentially weaken him and allow you to manipulate his energy as he is manipulating your friend’s. I saw a similar idea described brilliantly in a children’s fiction book once where the protagonist used a simple hand stamp to “mark” her victim. I can’t think of a better way of claiming power over somebody than stamping their hand with a personalised stamp and carefully blended oil mix. Unfortunately this isn’t very socially acceptable and probably constitutes assault so it isn’t something I can suggest!
Image - WPF owned