Sunil I am sorry you are struggling, I am also starting to deteriorate now after almost 2 years of my symptoms being very stable; now going downhill a bit as I sit around and wait for an insurance appeal and a consultation with a very overbooked specialist in tarlov cysts.
Something to discuss with Peter Dornan: In the Hesch Method practice i am involved in over here in the USA, treatment times are dramatically shorter, in fact clients who come to get SIJD corrected generally are able to be treated in only 3 visits over 3 days; they then leave either fully corrected or with a simple home self treatment regimen. The key to short duration of treatment is using a low load / long duration force. this actually imparts more total force than does a brief high velocity manipulation. Whatever manipulation is used on the SIJ in Peter Dornan's protocol, If it can be modified so that he can apply a sustained force of approximately 15 - 20 pounds over 2-5 minutes, the result of the manipulation should last much longer or even be permanent. Any stretches he has you do should also be maintained at comfotable end range without forcing, for 5 minutes. You will find there is a point in time at which something releases and your body begins to stretch further without effort.
The concept is "viscoelastic creep": the idea that body connective tissue has an elastic component and a plastic component. If you manipulate a joint or do a stretch for 30 seconds, you have effected the elastic components. it's like stretching out a rubber band: It might stretch and change for a bit but then will come back to its original shape. However, maintain a force for 2-5 minutes, and the "plastic" portion of the connective tissue is altered, meaning you have affected permanent change...just like stretching out a rubber band and holding it stretched out for a long time will permanently alter its shape.
I hope this makes sense; I am trying to find a way to shorten your course of treatment. It sounds like you have an excellent rapport with Peter Dornan so maybe next time you see him you could discuss this and see if he can modify his manipulations to apply force for a longer period of time. If he is manipulating the SIJ in the correct direction, and it seems he must be because you can feel the results, then adding a sustained time factor might help you dramatically.
I am not qualified to give you this advice as an authority, just suggesting you bring it up with an actual PT and get their opinion on whether it is worth trying.
All the best to you Sunil and i am sorry you are hurting
pelvic pain started 1985 age 14 interstitial cystitis. Refused medical care from age 17, did GREAT with self care for years.
2004 PN started gradually, disabled by 2009. Underlying cause SIJD & Tarlov cysts
improved with PT & meds: neurontin, valium, nortriptyline, propanolol. (off nortriptyline & propanolol now, yay!)
Tarlov cyst surgery with Dr. Frank Feigenbaum March 20, 2012.
Results have been excellent so far; but I won't know my final functional level for a couple of years.