My blood pressure is 93/40. i have been feeling dizzy and lightheaded. should i be concerned?

Yes if differ : Yes if it differ from your normal base line , what is your normal blood pressure ? Sounds like it's higher than above as a nor for you . Talk to your dr.

Maybe: You may be dehydrated. Many people have lower blood pressures and are completely normal. If you usually have high blood pressure and it dropped you may have a virus, be dehydrated, had alchol or have a medical problem. See your doctor if this does not easily resolve with fluids and salt in your next meal. Water is the best fluid as caffeine is dehydrating. Avoid alcohol which can cause this.