[MaeveChondrally (OP)]

if light has self gravity and each photons apparent mass is hf/c^2 and relativity is adjusted for this then we have a 5D model with Energy/Mass as the 5th dimension and spacetime as well (x,y,z,ct) then olbers paradox might be solved and explain why the night sky is dark mostly and explain that light attracts itself.

[evan_au]

electromagnetic radiation (estimated to constitute from 0.005% to close to 0.01% of the total mass-energy of the universe)...
Dark matter, a mysterious form of matter that has not yet been identified, accounts for 26.8% of the cosmic contents.

Sorry, electromagnetic energy (photons) makes up too little of the universe to account for Dark Matter.

The average photon in the universe has an effective temperature of around 2.7K, which makes it extremely low in mass/energy.

See: https://en.wikipedia.org/wiki/Universe#Composition

[Origin]

if light has self gravity and each photons apparent mass is hf/c^2 and relativity is adjusted for this

Energy is a source of gravity as shown by General Relativity.  Photons have no rest mass, so that is not a source of gravity, but photons do carry energy and that is a source of gravity.

then we have a 5D model with Energy/Mass as the 5th dimension and spacetime as well (x,y,z,ct) t

Energy/mass is not a dimension.  Dimensions can be looked at as a way to describe a location point.  Say I wanted to have a meeting with you, I would need to give an xy coordinate, like a GPS location, then I would have to give you a height the meeting was at, like the 4th floor and lastly I would need to give the time of the meeting.  Using those 4 dimensions and an appropriate coordinate system I can locate any point in space time.  Energy or mass would not help define a location.

As evan_au pointed out the amount of EM radiation is too small to account for the gravitational effects of dark matter.