Have you checked the other posts about itching? If you were doing an experiment, you would, of course, add only one thing at a time. But in this case, you need relief, so you should try many things at once, and maybe subtract later. I don’t mean medications. I just mean other things that can help.
For instance, did the itching just start recently? What else could be related? Go through a list like: amount of sleep (you may need more), time of the month ( the worst for me is right before my period), time spent in the sun (get some sun everyday), nervousness, winter dryness (be careful of over showering in the dry winter), overwork (give your body regular breaks), spices (I would try eliminating these if I were you. Cumin, cardamom, curry powder, chili peppers, jalapeño peppers are all taboo for me), anything unusual in your pattern. All these things can make things worse. And can you exercise more? This will help with the stress, but also with sleeping through the night. The worst itching can be 4 am to 6 am according to my hepatologist.
Also, are you eating enough fat? Try avocados every day. My own theory is to eat something with olive oil every day or two. Our illness means not eating high fat foods but we still need fat in our diet.
You may be panicking now, but remember things won’t necessarily stay the same, nor will they necessarily get worse. I’ve had a ton of itchiness at times, and now for a long time, far less itching. So do everything you can think of to improve things without medications too.
If you’re not regular, this can make things far worse. For instance, bran cereal before bed can help. Remember, there is a strong connection to the bowel with PSC so aim for short transit times. Coffee in the morning is highly advised. My hepatologist started me on coffee, and it really helps in many ways. He had read a study about it for PSC’ers. So I drink two cups every morning.