I was assuming that it might be that. Booting off an external drive would be an option but I believe it might be too slow as long it's not an SSD. Also didn't plan on spending more money on it for a new SSD.
Booting off an external drive won't be the best option, but it might work. You could try it with a USB stick if you have one big enough to put the OS on. USB3 isn't that slow, and flash drives are incredibly cheap these days.
It might be the SSD is dying? If you still want to use the laptop, can you boot from an external drive?