Question about late winter oxalic acid treatment

Hi gang,

This is my first winter as a beekeeper. Due to money constraints (thanks covid) I only have one hive at the moment. Somehow, I've managed to keep them alive so far here in Northeast Ohio.

We had a warm day last week so I cracked the hive open to check on the bees. They had plenty of food and there was a huge number of bees out stretching their wings. However, there was also a slightly concerning amount of dead bees at the foot of the hive and I did see a mite on a bee that had died up on the inner cover.

I had done a Formic Pro treatment in late summer/early fall, which maybe was slightly mistimed or less than fully effective. My question is if now would be a good time for an OA treatment before brood-rearing season goes into full swing. Should I do a mite count first? Should I just go for the vaporization treatment? Current temperatures are not suitable for Formic acid at the moment. I'm picking up my vaporizer today, as well as components for a second hive.

Thanks everyone.