Holy crap, you mean business. Never heard of nasal irrigation with baby shampoo! Can you smell it, or did the covid crush your olfactory nerve:)
6 weeks out from Moderna #4 with symptomatic covid reinforces (in my opinion) why most healthy people don't need 4th shots. Minimal, if any sterilizing immunity when hypothetically your nAbs should be raging high. Time to hang up the old mRNA vax and start fresh, or not at all.