The 3rd Alabama fought on June 1, 1862. During the battle, Colonel Lomax was killed and this may be why there is no after action regimental report. For some reason, General Mahone's (the Brigade commander) report cannot be found. There is a desciption of the 3rd Alabama's activity during the battle in "Third Alabama! The Civil war Memoirs of Brigadier General Cullen Battle, CSA" on pages 15-24.
Regimental loses at Seven Pines were 38 killed, 123 wounded, 14 missing. Total 175.
Shortly after, the 3rd Alabama was transferred into General Robert Rodes' "all Alabama" Brigade. (3rd, 5th, 6th, 16th, 26th Alabama)
If your relative returned to duty later in the war, I can help you with the movements of the 3rd Alabama if you're interested.