I am taking extra strength Sinutab tablets, 1 or 2 per day. The...

I am taking extra strength Sinutab tablets, 1 or 2 per day. The side effect, if caused by this medication seems to make me so tired. I wash the dishes, am played out. Make up my bed, am played out. Go downstairs and back up, am played out. My breathing seems to be natural. I walk for 30 minutes or more some days and I am no more tired at the end of the walk than I was after washing the dishes. Is it the Sinus tablets or is there something else that is my problem?