Hello and welcome to HCM.
It seems that red spots on your leg are hives.Hives can be provoked along with infections like sinusitis.
You need to get treated for sinusitis.
May I know if you have similar complaint of allergic reactions in past?
If you are facing symptoms of
acute sinusitis since 7 days like
cough,
nasal congestion,pain over face,bad headache (you have not mentioned about sinusitis related complaints you have),I would recommend-
-tablet
augmentin 500 mg thrice a day for 5-7 days(prescription drug)
-nasal decongestant spray twice or thrice a day for 3 days.
-steam inhalation and warm cloth compress over face.
-anti allergic like tab
cetrizine once a day for the hives (duration depends on persistence of hives,mostly hives resolve by itself in 3-4 days in such case)
You can return to me here for further clarification.Hope this helps.
Thanks and regards.