1. I had a stomachache, so i went to hospital.(have a stomachache)
>> I had a stomachache, so? I went to the hospital.
2. ?I ate something cold a lot yesterday, so now i'm running a fever.(run a fever)
>> I ate a lot of something cold ?yesterday, so now I'm running a fever.
3. You should do your homework right a away.(right away)
>> You should do your homework right away.