Are IUDs effective for birth control? Should I trust a woman I just met when she tells me I don't need a condom?

We get along fine, but on the first night she told me I don't need to use a condom because she uses an IUD and is STD free. I don't trust her completely, and so I used a condom. However I'm going to see her again.

I also don't see how she could be STD free if she's willing to go raw with me on the first night. What if she's done this with other guys? How would I know? Why does she trust that I'm STD free?

I don't know if I should trust her.

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And here's my second concern...

I used Edge Delay Gel for the first time that night. I might have used too much, but it burned and left my penis all red and sore.

Not only that, but my penis couldn't get hard. Like, it was tiny. Never had this happen before (I don't have ED).

Two days later and I can't get an erection to save my life. Doesn't matter if it's in person, my imagination, porn, or whatever. I can maybe get it up for a thirty seconds, but not much more, and even then it won't be fully hard.

Is this a problem I should go to the doctor for?

I'm freaking out and would like some advice please.