White smoke

Bought car three weeks ago. Last week when driving (had it serviced a week and half ago) I noticed white smoke from under the bonnet, opened bonnet, and white smoke with a burning smell was coming from behind the engine area but hard to locate where. Now when driving a lot of white smoke is exiting exhaust pipe and sometimes there is white smoke from behind the engine area. Drained some engine oil as it was over max and mechanic has scanned car but all clear apart from one faulty glow plug (have replaced that but still white smoke) Could it be DPF filter messing up? Engine cap seems fine no debris in there and coolant level is the same with no contamination so cannot be coolant leak. Slightly baffled. Mechanic is going to regen dpf on Monday but I do not think dpf is a problem or else it would show other symptoms such as warning light or higher idle etc. Any ideas of what tests I should ask the mechanic to carry out instead of regen the dpf?

Also, it is a burning smell not sweet which makes me think it cannot be a coolant leak.