About how stiff is a fully erect penis supposed to be? im not sure if mine is too soft or normal but its softer than it used to be.

NSAIDs and ED: If you have been having to use nsaids regularly for several weeks, this can have a negative impact on erectile function. The fact that at your young age you have a noticeable change suggests a possible link. Try avoiding these meds or use them in combination with other pain relieving techniques. It should be reversible. If it persists, follow up with a urologist should be pursued.