There are multiple causes for redness
and sensitivity to light.
It could be a corneal abrasion due to dust particle( which in your case is nil, as you have mentioned) or severe allergic conjunctivitis
causing swelling of the inner side of the lids and around the cornea or
A condition called uveitis
wherein the inflammation of the middle layers of the eye occurs and causes pain and photophobia
Even a Stye or pink eye can cause symptoms like this. And the treatment varies for each condition.
Have you been prescribed any medications? If you can update them then we can tell you what is the condition you are treated for.
If you are not comfortable even with the drugs, then review back with the same ophthalmologist or go for a second opinion
. Let us know how you are doing and hope you become alright soon.