My music suddenly came on really loud and had my headphones in but I have recently started listening to music at 33% will I still get hearing damage?

Noise induced. hearing loss can result from a single very loud noise or the accumulation of high frequency and high volume noise over time. A firecracker is one of the loudest non-occupational noises and it generates 180 decibels at peak; it can do damage. Loud car stereo or a rock concert generates 120-150 decibels. I doubt you did much damage with one headphone exposure but being more careful now is good!