Hi everyone. My son went for his boosters in Thursday. After we were told to keep an eye out for the usual symptoms. Had a bit of temp but that's gone now. What he has developed since Friday is a stiff neck. Like he has swollen glands. Just the left side, only so slightly. Nurofen gets rid of it but its still there this morning. Should I be worried or will it just go away in due course? Thanks in advance.