This is a very simple prayoga or spell, to Lord Hanuman. Lord Hanuman is a form of Lord Shiva. He appeared in The Ramayana as a friend and helper to Lord Rama in His epic. He helped Lord Rama. He helped Tulisdas, the person who wrote The Ramayana using this mantra. This has been my experience as well.

It's extremely simple, and this method is good for "emergency" situations, where there is not time to plan and prepare in advance for an "ordinary" prayoga. That's fine, but if you've got someone bleeding in front of you now, you need something immediate!

Get a forked stick, representing Hanuman's slingshot. One fallen off of a tree that you find will work fine. Consecrate it with water and with smoke. Jap the following mantra:

"LAAL DEH LAALEE LA-SAY, AROO DHAREE LAAL LAN-GOOR BHAJRA DEH DAANOW DALAN JAI JAI KAPI SHOOR"

Wave the "slingshot" over the afflicted area with your right hand while japping the mantra. Between mantras, gently blow on the afflicted area. This mantra needs to be repeated only 5 times - count them on your fingers! It can be repeated as desired or necessary,

No preparation or "special rules" apply (like food, drink, sleep, rituals). This can be done by anyone at anytime it is needed.

This was the mantra used by Tulisdas when he had problems, and Hanuman did help him. This has been my experience as well.

If you've got the time and ability, and it's not an urgent situation, you may add other things to this.

One thing is that you could add a Puja to Lord Hanuman, with Him as the primary diety of worship. You would offer all of the ordinary things, including prayer, song, mantra, food, a bath, and and incense. That would also entail casting a Hindu circle, which is quite simple. This would get you in better touch with Lord Hanumanji, but that is for you and the person you are healing. He will help you without the formal ceremony if you need and ask.

A simpler way would be to take a cup of water and bless it, and sprinkle that water first on the stick or "slingshot" before you begin, and sprinkle the water on the afflicted area between the mantras.

You could include a few Guru Mantra before and after. A typical Guru Mantra is:
AUM PARAM TATVAYA NARANYA GURUBYO NAMAH

Finally, you could end it with a "So Mote It Be!"