I had a very similar experience the first time I had a Pfizer shot, I think it's fairly common

Happened to me, got worse each booster. The initial shot had me feeling kinda drained for a day or two, second made me feel like I had a cold, third made me feel like I had the flu really bad. I haven’t gotten the most recent one yet because of how bad the last one was. All were Moderna.

A coworker of mine did exactly as you. He never described his symptoms and exactly how bad they were, but he stated that overall Moderna was the worst one, but far better than covid itself.

I haven't had the new vaccine yet, but after evading the old strain and catching the new one before vaccines were available, I can say... the original Moderna vaccine kicked my ass about equally as hard as covid's first day did.

(The cough is by far the worst part, but for me that didn't start until later, so the covid fever day felt completely identical to the post-vaccine day.)

Maybe you actually caught something while getting your vaccine

I've gotten Moderna for all my COVID vaccines so far. The only one to kick my ass was the second one of the initial shots. That one gave me a fever the next day, but I was able to call off work so it was okay. I was okay the day after, but sadly I had to go back to work.

I got off pretty lucky.

That was pretty much me a few days ago. I ate food that was a little hot, and I could feel it going through my insides for a little while, and it was painful. My fever was close to 103.

I've always gotten Moderna and just got my third (or fourth...I lost count) booster last week. This one was the first to barely bother me. I just got a little tired. The previous ones though were full beasts that knocked me out for 24 to 36 hours.

EDIT: From what I've read, Moderna's latest booster is supposed to be effective against the two strains rampaging about this year. Pfizer can only confirm efficacy against one.

Is there a chance you just happen to have gotten sick coincidentally around the same time that you got the vaccine?

Yes, my first vaccine was Pfizer and second was Moderna, which caused heart issues. I went to a heart specialist and was diagnosed with pericarditis from the vaccine. It took awhile for symptoms to improve (pain, shortness of breath etc.). I feel lucky though.

An unusual amount of people had severe symptoms in our area after the Moderna vaccine. Healthy people in their 30s for the most part. Our electrician had a heart attack and a few people died. Needless to say I didn’t go for a third. We know a guy who technically died from it, but he was revived - they got his heart going.

Yes!!! It's a great vaccine, I'll keep supporting our great pharmaceutical companies and happily inject myself with anything they produce. They have a great track record. Fuck those antivaxxers, they don't know what's good for them.