Is your drip tip metal or resin? I find with metal, if the juice spits, or even if the juice is too hot, I might get what I'd call a "shock" on inhaling it. But, that was SUPER rare.... I think Eskie is correct, though I'm unsure why it's happening NOW versus before, which is what makes me think it might be the tank, maybe you've lost an O ring somewhere (though, typically, that will cause leakage, also, but I'm not super familiar with your tank, maybe something has happened to it that's causing flooding, extra heat generation, and whatnot.) I'd try a different tank since you've already established it's not the mod, by swapping that out. Or, take it in to your local vape shop if they are good at figuring out stuff. If it's only happening occasionally, you might try a resin drip tip or notice when it happens.... Is it after you've vaped a lot? That makes me think it just might be heated juice or vapor even heating up the metal tip over time. That's my best guess, but I'd still try something else/take the mod in to be looked at.
If you are getting that "battery terminal" taste? (Surely we all licked 9V batteries as a kid... Maybe that's just me, LOL) Don't pass go, take whatever combination you have going on to your vape shop for a quick diagnosis. Or, switch tanks. I'm inclined to think your tank has a slow leak going on somewhere, but that's just me.
Good luck!
Anna