Thyroid & Tick panel anything else

Archie is still having episods on our walks where all of sudden he just gets out of control and starts biting at my arms and legs. It comes with no warning and nothing seems to trigger it. Putting him in a forced down sometimes works. This behaviour happens for the most parts on our morning walk. It's not playful biting, but at the same time it does not seem agressive - no growling or postures go along with it. He has no issues with the leash and walks well on a loose leash. He also has no guarding behaviour. When I walk him at lunch time he is great. These outbursts are just so outside his normal temperment and as said before seem to be limited to the morning. I'm thinking there may be something medical rather than behavioural going on. So I am going to ask the vet to run a Thyroid and Tick panel. Is there anything else I should be discussing with the vet?