I bit something hard and one of my front teeth felt a very tiny bit loose for a day or 2, now my whole front row of teeth feel tight+sensitive?? why?

Need more info...: To answer your question correctly, more info is needed: an examination of the teeth in question, radiographs, dental history, etc. Your teeth may have shifted slightly, your bite may be off, you may have fractured a root. A local dentist can help you determine what it is and what treatment is necessary. Make the call.

Trauma: Yu may have traumatized the area, doing damage to the tooth, the ligament that holds the tooth into the bone, or the bone itself. Depending on many circumstances this may require care. See hour Dentist for an examination and x-rays to establish a baseline and to determine if intervention is required.

Pressures: Stress to one or more teeth from biting something hard might have caused some shifting or inflammation. You might also be more conscious and worried about what might have happened which in turn may cause clenching or grinding. Best to have it checked out by your own local dentist to make sure it will resolve on its own and no treatment is needed.