Can constipation for 5-7 days cause symptoms such as headache, dizziness, fatigue, bloading, and just a weird overall feeling?

Yes it can. The body can react to physiological stress with toxic reaction. Patients prone to constipation can have severe autonomic reaction including hypertension, headaches, migraines, fainting spells, and even seizure like events. These may be severe is cases with spinal cord injury or in children with cerebral palsy. A "normal" person may have similar symptoms in an acute case of severe constipation.