If its fresh e.g there is a scab makeup will do nothing other than possibly give you an infection!
depending on where it is have you tried wearing some kind of support bandage saying you have pulled something? a medicinal bandage claiming ypu hurt your arm in an innocent way? a lot of bracelets? (possibly not if your male :thumbsup:) sweat band? buy more long sleeve tops? wash long sleeve tops very frequently so can keep wearing (highly impractical) wearing a cardigan thats thinner (e.g hoodies are hot).
Makeup wise i have camoflage makeup from the red cross but i rarely use it as it not effective at covering texture as mine are keloid scars but if it is new i reckon you will have a similar problem. However green helps cover red, you will need to use a concealer type makeup thats thick covered with a powder to help sort of set it and you will need it to blend the colour into the surrounding area .... it never very successful in my opinion.
Good luck :blushing:hopefully someone may have some better suggestions, i never show my scars and so am very well practiced at hiding them but it basically means i live my entire life in sleeves, i have a lot of cardigans etc :blushing: I also think you can find info in the ref section on covering scars