Medication not the same?

[Fcas]

My son takes Trimephoprim every day as a preventative due to Kidney problems.
The last prescription was completly different as in, there was no smell, which usually is a strong aniseed smell. Also, the latest is extremely thin where as previous have been similar consistency to calpol. Is it common for medication like this to differ so much? I understand medication will have slight variations, as to which chemist you use etc. But this just seems completly different. Should I speak to my doctor?

If you have concerns the medication you have been given is not correct then it would probably be best to return it to the pharmacy you got it from. There may be a simple explanation eg different brand. Ask to speak to the pharmacist. If not happy ask for a replacement. Doctor won't be able to help unless perhaps the prescription was changed?