He doesn't like going down on you, so you two aren't sexually compatible. However, he mentioned smell. This is coming from a guy's perspective; I have been with a fair amount of women, and did not enjoy going down on many of them. I just didn't find some of them visually appealing, they sometimes had a smell I didn't like at all, or another factor. There were a few in the past whom I didn't mind going down on at all. My current girlfriend, however, I go down on almost every time we have sex, I enjoy it a lot and look forward to it, it makes me happy and turns me on. Without going into too much detail, she looks very appealing down there, generally has no smell but does occasionally and its usually pleasant/appealing/sweet, and a taste obviously but nothing distinguishable. I also love her a lot and she can orgasm orally, every time and sometimes multiple times, which makes me happy, so even if I didn't enjoy the act that much (fortunately I do, a lot) I'd still do it for her.
I actually had a FWB situation end because she expected oral every time, for extended periods of time, was very demanding, rude if she didn't get it, had a weird taste and smell (the true deterrent), and to be honest we had great sex but I didn't love her, so I was not willing to be uncomfortable just to please her on that extra level.
Now I'm not saying this to give you any insecurities, many guys don't happen to talk about it often, but maybe he just doesn't find you very appealing down there? About the smell issue, the only times when its been an issue for me and my current gf is after a long day or first thing in the morning, and even then its not a huge deal. It shouldn't smell "bad" there ever I'd think, if it does maybe clean more often? Pubes can hold onto scent if he's not into that. His neck hurting is a bullshit excuse. Sometimes our tongues get sore, or whatever, that's not a reason. Otherwise, if you smell perfectly fine, have good looking junk, are hygienic, and he cares about your pleasure, but still doesn't want to go down on you, I think its time to find someone who does.