The amount of time you allow until seeking professional care would depend on the severity of your symptoms, and your prior experience with similar pain episodes. In the context of your narrative, it appeared that the presence of upper respiratory infection was established, and there was no uncertainty as to the presence of sinusitis. If this is not the case, or if your symptoms are not consistent with previous experience, this would merit more caution, and more prompt attention. Likewise, if you're not current with your dental check-ups, this would also suggest that the absence of contributory dental disease cannot be assumed, and would call for more rapid professional management. Until a diagnosis
is confirmed, any delay entails some risk of onset of more severe symptoms.
Because a presumptive diagnosis of sinusitis exists, the application of topical agents, whether garlic or oil of oregano, is unlikely to have any effect on the symptoms, as they would not penetrate to the affected tissues. As for gum recession
-- it could be associated with periodontitis, but because it can also result from other issues, such as poor tooth position or over-zealous toothbrushing, it is insufficient in itself to imply periodontitis without correlation with other diagnostic criteria. Your dentist would be able to assess your gums for inflammatory gum disease in the course of a routine formal diagnostic session.
Hope this helps...