So I was just wondering, my main character Marvin Rudges is now a level 5 Rogue. Of course his profiency goes up to +3. What i was wondering about is with the feat Expertise what they get is double their profiency to a selected skill. I was wondering that when a rogue levels up to level 5 do i add just one more point of proficiency onto that skill or does it gain two more points?.
Thank you and regards, Marvin Rudges
When you make an ability check, such as Dexterity (Stealth), you roll 1d20 and add you Dexterity modifier. If your are proficient in an applicable skill or tool, you also add your proficiency bonus. If you have Expertise with that skill or tool, you instead add twice you proficiency bonus.
So yes, your Expertise bonus increases by 2 every time your proficiency bonus increases by 1.
Just a general rule of thumb for 5E, abilities are never worse or better based on the level you got them. If there were it would lead to a lot of nonsense. For instance, if Expertise only doubled your proficiency when you first got it a level 19 cleric who took a single rogue level and then opted for expertise in stealth would be way better at stealthing than a level 20 rogue who took expertise in stealth at the start of his career.
ok cool thank you, yeah i thought that it would have a bonus of two every time profiency goes up just wanted clarification 
Thanks heaps
It just sounds like you are saying it strangely.....Your proficiency bonus is the same....+3 at fifth level.
But if you have expertise in the applicable skill, you would add +6 instead of the NORMAL +3. Skills you do not have expertise in still only use your normal bonus of +3.
That is an important distinction because there is nothing in the game that increases 'your proficiency bonus' other than gaining levels.