condom irritation or something serious?

so my bf used a magnum condom on me for the first time a couples days ago and my vagina feels irritated. i was scared that it could be a sti/yeast/uti hell idk or something but sex was fine until he used those condoms so i'm thinking that's the issue (plus i trust him). it's been like 2 days since. the irritation has calmed down a little but not all the way and the discomfort is just messing up my whole mood. has anyone else experienced this? he used trojan before and that didn't irritate me so i don't think it's a latex allergy but i could be wrong? 😕 i will say we DID buy lube after i told him what was going on (i lost my virginity to him so it's all pretty new to me) he says it could also be from the condoms drying me out. not to mention he's just well endowed. but we obviously haven't used it yet bc my vagina is on fire.