thanks for your query.
From what you mention , you may be suffering from nodule-cystic acne
.these are deep seated in the skin.Might be single or multiple in numbers and can be palpated better ;may be not seen as well.
This would require treatments with antibiotics orally or retinoids
,so you should check with a dermatologist
Other reasons why the cheek area is erythematous may be due to Rosacea
,where you see 'flushing' or erythema depending on certain stimuli.
Erythema in the malar (cheek )region is sometimes a sign of underlying connective tissue
disorders and should be correlated with systemic symptoms as well.
In all of the above cases, using a broad spectrum sunscreen with at least SFP 30 is recommended,hence would advise you doing the same.
Hope this is helpful.Take care!