You had a large gap of 3 months.. your muscles were relaxed all this while.. you have exercised and ur muscles are pumped up... there is wear and tear of muscle fibre..
it is called delayed onset of muscle soreness (DOMS) which is common after exercising..
Next Steps
Use cold pack if pain persist.. and consult a physiotherapist if pain doesn’t subside within 72hours..
Health Tips
Start from light to medium weights so that muscle gets use to the weights and exercises.. progress gradually.. be gentle with your body...
Make sure you warm up and cool down properly.. involve good stretching post exercise...
have protein Intake and good sleep for fast muscle recovery..