Hi There. I Was Prescribed Erythromycin Today (250mg, 4 Times

Hi there. I was prescribed erythromycin today (250mg, 4 times a day) for a chest infection and was wondering if its safe to combine 'Beechams All in One' (paracetamol, phenylephrine, guaifenesin) with this, as dramatically helps.
I also have tonic-clonic epilepsy, so take pregabalin (50mg twice a day) and levetiracetam (750mg twice a day) together. Considering my breathing becomes tighter at night due to chest infection, I need to know whether this will be safe altogether. Thankyou kindly.