You have been given some good advice. In my experience, for indoor sports, lens speed is of primary importance. When shooting night time high school football lighting is poot. your75 to 300 mm zoom lens would be OK outdoors in daylight, but for night football and for indoor volleyball or basketball it is too"slow" which refers to the maximum aperture value, which I believe is f/5.6 above around 225 mm in length.
if you do not have a zoom capability in your lens,then you must move yourself and the camera closer or farther from the action, so there are a number of prime or single focal length lenses which would be good for indoor sports such as from very close the 24 mm wide angle lens or the 35 mm F/2 (affirdable!) Lens, Or the 50mm F/1.4 lens, or from a moderate distance,the 85 mm F1.8 auto focus lens. For night time football from the bleachers there really is no good lens that you can likely afford… Shooting from the bleachers is not nearly as good as moving 50 to 100 feet closer to the action and using a lens that does not cost $10,000 and weigh 12 to 15 pounds ( I am speaking of a 400 mm F/2.8 Canon EF ). from the sidelines I would think that the shortest lens you could possibly use would be the 135 mm F/2.0 Canon L-series, or the 200 mm F2.8. These two lenses are amazingly sharp and relatively light and fairly easy to use.
Another popular sports lens is the 70 to 200 mm F2.8 L, which has recently been upgraded to the Mark III iteration, and it is an exceptional lens ,but it is F2.8 not F1.8 or F2. The typical high school football field does not have very good lighting at night, and it's nowhere near as bright as most college or professional stadium fields, so lens speed, meaning maximum aperture value, is a primary importance when shooting night time high school football. In some parts of the country, junior varsity and lower levels and sometimes varsity level football is played during daylight hours and this is much less demanding of equipment.
Coming back with sharp,clear high school sports photos...it's not all equipment....there is quite a bit of demand placed upon the skill of the photographer.there is no one "best lens". I think you need three different lenses, ideally.and quite a bit of experience.if I would recommend just _one_lens however it would be the actual Canon 70 to 200 F 2.8.