Hi, You had any feeling of yourself or surroundings spinning around (suggest vertigo)? If not, a sudden feeling of tiredness and dizziness (feeling of falling down) while walking indicates vasovagal syncope rather than vertigo. This occur from postural hypotension, whereby blood flow to brain decreases transiently. This is a common event when we return from a heavy day, especially when fluid intake is insufficient or had inadequate sleep the previous night. During any such further episodes, just lay down with limbs elevated for few minutes (sit if not possible) and drink some fluids. Always take adequate rest in between work, and drink lot of fluids to prevent this happening again. In case your symptoms fits into vertigo, vertin tablet might help. Review with your doctor for further evaluation if symptoms not getting fine in 2 days, and avoid self driving until resolved. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Muhammed Aslam T. K., Pediatrician