welcome to HealthcareMagic
The problem of sinus
is fine if Zyrtec
helps you so you may take it as needed and occassional streak of blood if you blow the nose is fine as it can happen due to forced blowing.The main issue you are worried is the bleeding in stools and that is probably due to constipation
.As you did not have bowel movements from Mon-Wed so you will suffer constipation and to evacuate and get relieved you may have strained which has resulted in bleeding.Presently just keep a watch whether you have bleeding again after stools and if yes then you may be having piles and you will need to get treated if required.