Please keep in mind you are talking to a second year here so here goes- You made my day!
SO glad you found a wand and treated them. The 24/48 hour mite drop on your sticky board will tell you a lot. If you go to mitecalculator.com it will give you an idea of infestation rate after 24 hours. So if you don't have a sticky board you can buy or make them from white coroplast (Home Depot) and oil them. I also use coroplast for hive awnings. Vino does too. Some use Crisco. I use olive oil. I'm on round 3 on the high mite count hive and finished 2nd round on 3 others and one round only on my nuc. From everything I've read you have to interrupt the breeding cycle of the mite. If you don't kill them, they will reenter a new cell before it's capped. I'm doing a more intensive treatment on my high count hive because my numbers aren't static. I think they're robbing hives outside my apiary and becoming re infested. So I have to treat every few days while the acid remains active in the hive.
To your point about Apivar and OAV. I'm doing a bit of that myself. Only had one strip left for the high count hive so I decided to put it on. Love Apivar but it's not like the flash treatment of OAV. OAV knocks the crap out of the mites very quickly but does not get under cappings. You also have to do a series of treatments to cover the brood cycle. The short answer is- it's generally not a good idea to combine treatments but sometimes you have to break the rules- selectively. No doubt more experienced people will have opinions on that one.
I think I have a pretty good handle on this one now. Starvation is #2 and moisture is #3 for me are next on the hit checklist. Fed aggressively in September (4-5 gallons each). Added vivaldi boards to solve the moisture issue. Continuing to fine tune that one. Wishing you the best.