Pseudophedrine- galpseud and Cetirizine

Morning,

I have had an ear infection for about 2 months which was unsuccessfully treated by amoxiciliin as I took an allergic rash and was advised to stop.  As an alternative my doctor has prescribed psudophedrin-galpseud, a decongestant and Cetirizine an antihistamine as my sinuses and ears are blocked.  

I have been taking the antihistamine but am apprehensive to take the Pseudo-galpseud (3 x a day) as there were no instructions with the bottle.  Can I take at the same time as the antihistamine?  and it is safe?

If I don't take the pseud-galpseud but were just to take antihistamine would that be enough to clear my sinuses and ears?

Thanks,

SA