Sign of impending miscarriage?

I am on my 3rd pregnancy (one live birth and one miscarriage within the last. 2 months). I am currently almost 5 weeks pregnant. During implantation, I experienced strong cramping and mistakenly took 400mL ibuprofen. From that day on (for a week and a half) I experienced intense fatigue, lightheadedness and dizziness. 2 days ago I took my toddler to a trampoline place. I didn't jump, but I gently bounced up and down with him and ran a little. After that moment, throughout the day I felt a dull, burning pain in my abdomen. Yesterday my abdominal pain disappeared, but now the burning sensation is back. Yesterday and today, my fatigue and lightheadedness have markedly abated. I went in to get my Hcg level checked - it is at 379. I have to wait a couple of days to determine if the Hcg level is decreasing. Is strong dull abdominal pain like this, after physical exertion, with an abatement of pregnancy symptoms, an impending sign of miscarriage?