i think your chest infection
must have cleared by now, some times traces of blood do come in mucus when there is severe infection, if you get again you can visit your doctor for check up. if it has stopped after your infection is cured then you can stop worrying about it.
now about your asthma, plumicort 200 which you take is budesonide
, which is steroid
. and symbicort which your son uses is budesonide plus a long acting broncho dilator. ideally when inhalers are given it is adjusted to minimum dose at which patient is comfortable. since you where comfortable on pulmicort
200 you should continue the same thing. but for now until you get medical attention you can take symbicort 100 ,4 puffs 2 times , if you have heart problem or you are old you should go to your doctor before starting your sons inhaler.
your symptoms of asthma increased due to your lung infection
after 2-3 days you will be fine like before, and you will be comfortable on your inhalers itself