After yesterday’s splendid bike ride, I got a flu shot. For dinner we ate mass quantities of Five Guys food while watching the Nationals game. They won. Miracles do happen.
During the game my left arm ached as if someone had punched it hard. I went to bed only to toss and turn all night as the Five Guys re-arranged my GI tract.
I left the bed and slept on the couch hoping the change of venue would bring relief. No dice.
Now it’s past midmorning. The weather is perfect once more and I feel like I have a hangover. No energy. Slight headache. It’s the first time I’ve felt remotely ill since last winter.
Of course, I could have Covid. Ayyyyyyy!
Unlikely.
So I’ll sit on the deck and drink fluids while reading The Martian (very entertaining). At 1 I’ll go inside and watch the ballgame. I’m hoping by 4 I’ll feel up to a bike ride. I’d hate to waste this weather.
A Few Spokes Shy of a Wheel 
Sounds to me like you caught the Five Guys physical discomfort! If I eat thing like this I get a “hangover” like feeling for a full 24-48 hours.
Just had some antidote: chicken soup. I’m a medical genius.
Is it possible you got your first ever administration of Fluzone High Dose? You just turned 65, yes? If you got it, it’s a more potent vaccine, and what you’re experiencing is your immune system kicking in with a defensive reaction – that’s a good sign. Hope you’re feeling up to a ride later.
Yes. It’s my first high dose. Thanks.
I got sick after getting my flu shot last week. I also got a pneumonia shot in the same arm. Both are stab wounds into the arm muscle. Either one is painful. Two in one arm is excruciating. Like you, I was up all night.