The active ingredients in Calpol Night, Calcold, Medised and Dozol are Paracetamol 120 mg, Diphenhydramine hydrochloride 12.5 mg per 5ml spoon.
However Dozol is the only one available from 2+, all the others are available from 6+.
So, either buy Dozol or if you want to continue with the others you can pretend it is for a 6 year old in the knowledge that is actually safe to give from 2 years old. Medised was originally available from 3 months+ so if you decided that you still thought it was safe to do so you could use the following doses for any of the above medicines.
The original doses for the 3 months+ Medised are:
Under 12 months: half to one 5ml spoonful 3-4 times a day
12 months to 6 years: one to two 5ml spoonfuls 3-4 times a day
6 years to 12 years: two to four 5ml spoonfuls 3 times a day
You nust leave at least 4 hours beteen doses and give no more than 4 doses in 24 hours.