Need Help What Coin Is This And Its Value

It says cos 2 on the reverse not 3
and tell me wich side is dark to take annother pic

Have a look on Wildwinds, RIC 88, can't hotlink to it.

Why do you think it is fake ?

The coin looks better in new pic but still hard to determine whether it is genuine.
Sorry to say but one red flag is your location ! Too many "fake" coins have been coming out of the Balkans in the past twenty years ! Serbia and Bulgaria in particular have been noted as the source of many highly questionable (and high quality) fake ancient coins. As you are geographically close to both it makes a sceptic think of this as being very possible ! Some have even planted fake coins among real ones found in order to convince those who question !
This is a great shame as your area is known to be rich in buried treasures.

Knowing where you acquired the coin could be helpful. But even then we have found that some fakes have turned up where they were planted in the ground in order that the coins be considered as "genuine" finds.

Either way while it is a nice looking coin a denarius of a "young" Caracalla is not worth what you might hope. The denarius was superseded by Caracalla with the 'double denarius' or antoninianus later in his reign. I can tell it is a young Caracalla by his lack of beard and the smiling face. The older Caracalla is almost always growling and has a rather terrifying look. He was a very vicious man ! The output of the denarius in his early years was tremendous ! Extremely fine condition denari with a common type reverse (Mars is a common type) will often sell for $30. In this condition sold on ebay you might get $10-15.
Sold from your location might get even less ! Trust is everything when money is concerned.