If your blood pressure is normal, urine does not have proteins or sugar in it, probably the head ache and congestion is not related to pregnancy complications but could be due to flue, common cold or such upper respiratory tract infection. Initially, you may try steam inhalation and some pain killer (which should not have aspirin in it) for temporary relief. Your doctor after examining you will decide whether you need any antibiotics. If your mucous plug has been dislodged, that means your cervix is almost prepared for labour pains. I have got a feeling, by the time you get this answer, you might have landed into labour. If not, you are going for scan as per your schedule. Till that please keep a watch on the movements of the baby. If they become less, please report to your Obstetrician immediately.