25 days post op Facelift, I have been using Johnson's Baby Shampoo and it's causing itchiness on my scalp. Any suggestions?

Did you also have a browlift?  The nerve regeneration could be causing the itching.  You could also have a sensitivity to the shampoo, or could be drying out your scalp with frequent washes.  Once you have cleaned your scalp thoroughly after the surgery, you shouldn't need to be washing it daily which can dry you out and make it very itchy.  Switch to your normal shampoo which did not cause itching in the past, and only wash a couple of times a week with the shampoo. 

If your scalp is irritated by any shampoo you should probably look for a replacement. Generally shampoos without fragrance are better But are hard to find.

I would see your PS for advice but I would probably stop your current shampoo and try another product. There is no reason why your scalp should be so itchy and it may be worth not using any shampoo for a couple of days.