The question of how many extra tablets were taken can be recast in a way that avoids the question of how many days earlier Wednesday is than Friday. See beolw (by the way - at the time I was sleeping during the day and that's why I was taking the tablets at 2pm)


On these each of these occasions

Friday 2pm 
Saturday 2pm
Sunday 2pm
Monday 2pm
Tuesday 2pm
Wednesday 2pm
Thursday 2pm
2nd Friday 2pm
2nd Saturday 2pm
2nd Sunday 2pm
2nd Monday 2pm
2nd Tuesday 2pm

you take 2 or 3 tablets and you take 28 tablets in total. How many times did you take 3 tablets?


Simple trial and error tells you that the only way you end up taking 28 polos in total is if you take 3 tablets on FOUR of the days:

Friday 2pm took 2
Saturday 2pm took 2
Sunday 2pm took 3     
Monday 2pm took 2
Tuesday 2pm took 3    
Wednesday 2pm took 2
Thursday 2pm took 3   
2nd Friday 2pm took 2
2nd Saturday 2pm took 2
2nd Sunday 2pm took 3 
2nd Monday 2pm took 2
2nd Tuesday 2pm took 2

Total  = 28