Part 107 UAS pilot reported a near miss with a helicopter during cruise flight.

Narrative

On Day 0 at XA:34 am I had a close encounter with a helicopter.I was doing a practice mapping exercise. The drone was executing an automated flight plan under the control of Dronelink. I had my eyes on the drone. I was at the controls. The drone was flying at 100 feet AGL heading true east at XXXY ft geometric. I requested and was granted LAANC permission to fly at 100 feet before the flight.A helicopter appeared approaching from the south and banking hard west. It was at XXXZ' and 79 knots according to Flight Radar 24. This is an air ambulance based at a helipad 0.7 miles away on the roof of a hospital. The elevation of the helipad is XXXX ft.There was a very short time to react between when the helicopter presented itself and when it passed at its nearest point. I was near two story houses; so I did not see the helicopter until it was very near. Since the drone was already headed east at 10 miles per hour I thought the best course of action was to continue east and then monitor the helicopter to reassess.