4 weeks into flowering, nute burn or mites ?

So i am 4 weeks into flowering. Is this a nute deficiency , nute burn or spider mites. I look around and under the plant and cant seem to catch any mites hanging around. I watered my plants today but only 6.4 water and 3 tsb dololime . If they are low on nutrients what should i do give them more amount on feeding. Wouldn't that burn them even more ?
Thanks...