Flu-like symptoms after working out dormant muscles

[BillieGates]

Hi everyone,

So the other day I did a push workout, but did it properly and got a pump- which I've never done before in my life. I have a super weak upper body to the point of neck problems, just so you have an idea of just how unused the muscles in that area are.
After getting a good pump (to my tiny muscles lol) I went home and everything seemed kinda okay, until I went to bed that night and a raging headache set in. It was so bad not even a couple of Advil could ease the edge. I woke up the next morning, and all the next day I had flu-like symptoms. My nose was itchy all day, I had a slight headache and my eyes felt weird.
Later in the day I went back to the gym to do my usual leg routine, and again, when I go to bed my head is splitting! Advil helped this time though and waking up this morning I feel a lot better than the other day.

I have heard that massage can cause flu-like symptoms due to metabolic waste being freed from the muscles, and I've had allergic reactions to remedial massage on my calves after a bad knot before, accompanied by a pretty sore head and a stuffy nose. I was thinking that maybe because I've never worked out my chest/delts before, that maybe the workout stirred up some stagnant waste and its knocked me around.
Does anyone else experience allergic reactions like this? And is there any fast way I can get my body to flush it out so I don't have to suffer like this?