115 is LOW
90 is damaged
Pretty much the only way to know for sure is to tear it down and inspect the parts.
It is VERY common to have a bad valve.
It's an easy test. With the head off spray brake clean down the intake runners If it leaks past the closed valve you have a problem. Then flip it over and test the exhaust side by spraying down the exhaust runners.
Durring winter months a lot of people take their wheelers out and drowned them in water. Bending rods, killing rings and doing all kinds of damage by sucking water into the engine.
With that low of compression at VERY LEAST you have a bent rod, bad valve, or bad rings. No matter how you cut it. It needs a rebuild.