Retained tick head - what to do?

[Pringle89]

My pup has had three ticks in the last two weeks despite trying to keep clear of long grass.

I removed two and they were intact, one of the areas has a raised white lump - doesn’t look red or infected, is this normal? Also he managed to scratch one off his nose but left the head in the skin - was already dead I think..again almost looks like a crater with a little black dot in the middle. Do I leave and let nature take its course and expel the head or do I need a visit to the vet?

Also just found out his flea treatment doesn’t kill ticks so will be changing this - any other recommended treatments/repellents?

Yes, we do treat stray with Frontline when we can, also Drontal 'spot on' wormer, although not as regularly as should as a bit hit and miss! He lives in the overgrowth at the back of the field over the road which is where he must be picking them up! Lovely old cat but all attempts to entice him in have failed
Here he is

Sorry, realise this is 'the doghouse'. Will buzz off now!