Arm Strain while sparring

Hey I’m posting this to find some advice or tips to help my case. I’m new to Muay Thai and combat sports as a whole. I have been all my life in sports and I’ve been before going to Muay Thai lifting for around 4 years. But ever since 3 months I stopped going to the gym and now I train 5 times a week Muay Thai. I’ve noticed when sparring my left arm after hurts bad in the bicep region causing it pain and not able to lift it up sometimes. I am orthodox stance. Idk if it’s because of my punches or when I do my clench. I appreciate any tips or workouts I can do to improve this.