Im very allergic to penicillian and amoxicillian ( the mold in the meds) so whenever I get sick I pretty much get prescribed the z pack.. I usually dont start feeling the relief until the 3rd or 4th day which is weird because its such a short time frame to take the meds for. If you still feel no relief in the next few days then you should head to the hospital. I had some sinus issues in the beginning of this pregnancy that thankfully never fully developed into an infection but my dr as well as my pharmacist told me for relief I could take sudafed.
Try a saline nasal rinse for lower sinus infection. If it's upper, search friggy flip turn sinus rinse. This was before pregnancy but no meds were helping until I did the flip turn. I swear you'll be amazed by the nasty infectious materials coming out. Just be careful, there is another form of the flip turn since your balance might not let you stand and do it. Can cause light headedness from getting up quick
Feel better