I Am Worried About My Dad's Behaviour, Should I Be More Concerned?

My dad is constantly on his phone, and can sometimes be quite secretive about it, but when I check it I don't find any weird texts from other women or people. I have also been finding empty alcohol bottles stashed in weird places (in his backpack, under the seats in his car, under his bed) yet he never seems to be drunk. There is also a lot (and I do mean a lot) of pornographic material on our shared computer, and I am sure it is his because besides me, he is the only on who can work a computer well enough to hide it. I don't know what to make of all these findings, as they are all recent, but I am worried. What would you think if you found all these things and what would you do? Should I talk to him about it, which would be very uncomfrotable for me as I am a teenage girl, or should I tell my motther, or just not do anything? Please help me!