Hi, I'm 18 years old; today I have noticed the hearing in my left ear to be significantly reduced, to the extent that I can hardly hear out of it.
I cleaned my ears using cotton buds, but it just made it worse. This all happened just over today.
What should I do? Will it fix itself?
Please don't use cotton buds in your ears, not very good. Maybe you have a build up of wax, the cotton bud will have pushed it down more. A visit to the nurse or Dr will be best to check, they can syringe your ears to clear the wax . thats probably 1st step. If its not wax the Dr can refer you to ent dept if necessary. Could also be an infection. A Dr visit best to check it out
Hey, I'm going through a similar experience with my hearing. It can be caused by a build of fluid pushing onto or flooding certain tubes in the ears. This changes pressure and can create painful level of deafness.
If you got a pharmacist first they can check it out and can often do what most doctord can do. If they aren't much help just make a quick visit to the GP to see a nurse or a doctor.
Avoid using earphones and loud appliances. It should all be cleared up within a few weeks 
Anyone who suffers any sudden hearing loss should see a GP as soon as possible. Many times it will be caused by wax or an infection which are easily treated, but it can also be Sudden Sensorineural Hearing Loss (SSHL), which needs immediate treatment to try to prevent permanent hearing loss.
I suddenly lost the hearing in my left ear and went to my GP that day expecting to have the ear syringed to remove wax. My GP told me there was no wax and immediately sent me over to the ENT consultant at the hospital. He took one look and within 2 hours of seeing the GP I was admitted to hospital as an emergency for steroid and 100% oxygen treatment. That can sometimes restore the hearing in cases of SSHL. I was kept in hospital for four days, but unfortunately my hearing didn't come back and I've been totally deaf in my left ear ever since. I have since had surgery and had a bone conduction aid fitted.
Apparently 9000 people in the UK suffer SSHL every year, so nobody should be casual about it. If you lose your hearing suddenly, to have the best chance of getting all or some of it back, go straight to your GP.
99% wax build up, get them suctioned.
Tabby-cats advise is very correct here. If you can't see your doctor fast just go to A&E with hearing loss, treatment is available, but needs to be done quick and fast to have chance of success or to limit the damage caused. Like so many may things you don't know before it happens to you, what damage can prevented, just like quick action with a stroke.
Severe hearing loss
New to hearing loss - Help 
What is your best tech for hearing loss?