Was my drink spiked?

I went out with my boyfriend and two friends 2 days ago but something just feels off. I had 4 redbull vodkas at home and was feeling a bit tipsy, we then got on the bus and went to the club. At the club I got another redbull vodka. After that I can’t recall anything that was going on for the rest of the night. I remember that I was leaving my cup at the table next to me so I feel like if anybody wanted to spike my drink they definitely could have. I’ve been drinking for quite a while and I can usually handle a lot of alcohol so forgetting the whole night after 5 drinks seems really weird to me, in fact I’ve never forgotten the whole night even when I drank 15+ drinks before. Even 3-4 hours after drinking that drink I can’t recall anything, I don’t know how we got home and I can’t remember being home at all, if I was just drunk wouldn’t I have started to sober up at that point? The day after I just felt like I couldn’t think at all, but I wasn’t feeling sick or anything like that. Is it possible that I was drugged or does this just sound like I was drunk?