I think he could tell us the volume of blood that will reach the affected area, or by hemodynamic the region may indicate the inflammation and thus take care of the possible cause.

Are you asking how/why ultrasound can relieve pain? Therapeutic ultrasound can be used to increase blood flow to an area of the body which promotes healing and relieves pain. It's similar to getting a tense muscle massaged, which feels good because the massage helps that muscle relax and regain its normal blood flow and function. Since ultrasound (like all sound) is a pressure wave, it's analogous to a very targeted, very gentle massage.

Ultrasound induces heat in tissues, and therefore capillary vasodilatation, and this increases the blood flow to the area. Anti inflammatory mediators reach the site easier. Also with a similar mechanism, there is a combined effect of muscle relaxation along with the local temperature increase. there is a combined effect of all.  The physiotherapeutic ultrasound probe is gently moved over the tissue adding to the relief of pain through massage effect. 

However, you should be careful and double check, because there is a possibility of migraine getting worse with vasodilatation.   You may precipitate a migraine attack.